The objective of this project is to gain some understanding on the role of two early gene functions of papova viruses in neoplastic transformation: the hr-t and ts-a functions of polyoma virus and the d1 and tsA functions of SV-40. The questions to be asked are the following: (1) Can both the hr-t/dl and the ts/A viral genes control the cellular transformed phenotype? (2) Can the ts-a/A gene regulate the expressin of the hr-t/dl gene? (3) Can the hr-t/dl function only induce cellular genes in the proximity of the integrated viral genome? (4) Can viral gene expression become under cellular control, and if so, how? To answer these questions, ts-a/A transformants which display either a temperature-sensitive or a temperature-insensitive transformed phenotype will be studied with respect to the production of viral proteins and viral mRNAs, and the patterns of integration of the viral genomes.